The present invention applies to a communication network in which data can be transmitted from a sender to a receiver via a number of intermediate network nodes. Data can be transmitted via different routes, usually comprising one or more of the intermediate network nodes. A direct path between two adjacent nodes is referred to as a link. Depending on which communication links are used for a communication flow different transmission routes (or paths) through the network from the sender to the receiver can be distinguished.
It is important in any such communication system to optimize the selection of the routes to utilize the resources as efficiently as possible.
In existing routing solutions a route selection is typically based on assigning a cost value, or metric, to each communication route, that is, a route metric. The route metric is generally determined as the sum of the metric values for all links, or hops, in the route. The link metric values are often used to reflect the “quality” or utility of a particular link in relation to some performance objective. Typically, but not necessarily, each node determines link metric values for its own link interfaces and the values are distributed to other nodes using routing protocols. The best route is typically selected to be the route that has the best route metric.
In the prior art as described above each link is considered independently. The possible effect on a link of changes in any other link is not considered.
The “quality” or utility of a link can be affected by what happens in other links. This can be the case, e.g.,                for different links sharing the same medium or channel, for example, the same CSMA medium used for transmission on different hops, with joined contention        different links transmitting on different channels which interfere with each other, for example, different radio access technologies using the same or adjacent spectrum        transmission of different links using common processing power, memory or other common resources, for example, if the links are within the same node and use the common DSP, RAM resources        
In multi-radio multi-hop networks, usually a number of different links exist to and from the communication nodes, the links using different radio access technologies or channels. In such a scenario, a routing decision where the route metric is only considered based on the individual link metrics leads to a non-optimal solution, since the interfering effect of different links in a route is not considered.